1. Field of the Invention
The invention relates in general to a flat panel display panel, and more particularly to a liquid crystal display panel.
2. Description of the Related Art
A passivation layer is generally applied over the surface of the thin-film transistor substrate of a typically reflective thin-film transistor liquid crystal display (TFT-LCD) panel or a trans-flective TFT-LCD panel. A photoresist (PR) layer is further disposed on the passivation layer within the active region of the panel and serves to modify the distribution of the reflecting lights. The modification of the reflecting light distribution is accomplished by forming an uneven photoresist layer within the active region of the panel and then forming a metal layer thereon. The photoresist layer surrounded around the active region offers a base for numbers of rod spacers to keep the cell gaps on the edge of the display panel uniform.
Referring to both FIG. 1A and FIG. 1B, the former is a schematic diagram of a conventional LCD panel and the latter is a cross-sectional view of a portion taken along line 1B-1B′ of FIG. 1A. A LCD panel 100 includes an upper substrate 110 such as a color filter (CF) substrate and a bottom substrate 120 disposed below the upper substrate, like a TFT substrate. The LCD panel 100 including the CF substrate 110 and the TFT substrate 120 is divided into an active region 130 and a binding area 140. The binding area 140 is surrounded around the active region 130.
Within the binding area 140, sealant 112 is employed and dispensed between the CF substrate 110 and the TFT substrate 120. There is a passivation layer 122 as the first covering layer on the TFT substrate 120 and a photoresist layer 124 as the second covering layer on the passivation layer 122 within the active region 130 and the binding area 140. The passivation layer 122 is made of silicon nitride (Si3N4) or silicon dioxide (SiO2) and the photoresist layer 124 is made of organic materials.
The photoresist layer 124 above the TFT substrate 120 of a conventional LCD panel contacts with the sealant 112 within the binding area 140. Then the CF substrate 110 and the TFT substrate 120 are pressed by a jig and the LCD panel 100 is baked in ovens to harden the sealant 112 so that the CF substrate 110 and the TFT substrate 120 can be adhered to each other.
The adhesion between the sealant 112 and the photoresist layer 124 is firm and tight. However, the affinity between the photoresist layer 124 and the passivation layer 122 is not so. Due to the particular material characteristics of the photoresist layer 124 and the passivation layer 122, the junction 123 thereof presents low strength. Cracks can easily generate between the photoresist layer 124 and the passivation layer 122 when the LCD panel 100 is subject to an impact test or a vibration test (a dependence test or a fall test). Such cracks will degrade the performance of the LCD panel 100 or further damage the LCD panel 100.
To sum up, low strength is one of the disadvantages of the conventional LCD panel 100, which therefore generates cracks around the junction of the photoresist layer and the passivation layer and causes inferior panel quality.